when I pull the inside hood release on our 2003 xk8 the drivers side hood release is good, but the passenger side will not let the hood open

 

There are 2 cables, one for each side and both operated by the hood release. I had the same problem and it was caused by the release handle breaking on one side and not pulling that cable. A new release handle ( about £25 if I remember correctly) solved the problem but a temporary fix is to pull the affected cable using mole grips or similar.
Good luck
Pete